MSFS20 unknown wasm error

[mariomotta]

hello
i'm receive this error from the in-game dev console:

WASM: Exception c000001d in gauge warning_panel in module
 P:\MicrosoftFlightSimulator\Community\mycompany-aircraft-wasm-gauge\SimObjects\Airplanes\MyCompany_Gauge_Aircraft\panel\ssw_shared.wasm

nevertheless the module is compiled, initialized and loaded correctly, it works nicely as well.
Someone had same issue ?
Below the module code,
the SetRpmOverspeed() is triggered by a custom event originated in the behaviou xml when the PROP RPM overtakes 2600 rpm.
tia
/mario

#include "ssw_shared.h"
#include "simvars.h"
#include <engine.h>
struct S_WLIGHTS
{
    int iFont;
    NVGcontext* nvgctx;
    LocalSimVar* rpm_overspeed;
}; 
//////////////////
S_WLIGHTS wlights = {-1,0,0};
extern Engine* myEngine;

void SetRpmOverspeed(FLOAT64 overspeed) {
    if (myEngine) {
        RWSimVar* prop_rpm = myEngine->prop_rpm;
        RWSimVar* throttle = myEngine->throttle_pos;
        wlights.rpm_overspeed->Set(overspeed);
        if (prop_rpm && throttle && (prop_rpm->Get() > 2600)) {
            FLOAT64 thr = throttle->Get();
            thr -= 0.2;
            throttle->Set(thr);
        }
    }
}
///////////////////////////////////////////
///////////////////////////////////////////////////////////////////////////////////////////
void DrawWarnings(NVGcontext* nvgctx, sGaugeDrawData* p_draw_data, struct S_WLIGHTS* data) {
    if (data->iFont != -1) {
        char str[50] = "";
        //////////////////////////////////////////////////////////
        nvgFontFaceId(nvgctx, data->iFont);
        nvgFontSize(nvgctx, 0.20 * p_draw_data->winHeight);
        nvgTextAlign(nvgctx, NVG_ALIGN_LEFT | NVG_ALIGN_TOP);
        nvgFillColor(nvgctx, nvgRGB(250, 0, 0));
        if (data->rpm_overspeed->Get() > 0.0) {
            sprintf(str, "RPM OVERSPEED");
            nvgText(nvgctx, 0, 0.10f * p_draw_data->winHeight, str, (const char*)NULL);
        }
    }
}
////////////////////////////////////////////////
extern "C" {
    
    MSFS_CALLBACK bool warning_panel_gauge_callback(FsContext ctx, int service_id, void* pData)
    {
        
        switch (service_id)
        {
        /**/
        case PANEL_SERVICE_PRE_INSTALL:
        {
            
        }
        break;
        ////////////////////////
        case PANEL_SERVICE_POST_INSTALL:
        {
            NVGparams params;
            wlights.rpm_overspeed = dynamic_cast<LocalSimVar*>(GetSimVar("rpm_overspeed"));
            ///////////
            params.edgeAntiAlias = true;
            params.userPtr = ctx;
            params.edgeAntiAlias = true;
            params.userPtr = ctx;
            wlights.nvgctx = nvgCreateInternal(&params);
            if (wlights.nvgctx)
                wlights.iFont = nvgCreateFont(wlights.nvgctx, "serif", "./data/Roboto-Regular.ttf");
        }
        break;
        /////////////////
        case PANEL_SERVICE_PRE_DRAW:
        {            
            /// /////////////
            sGaugeDrawData* p_draw_data = (sGaugeDrawData*)pData;
            float pxRatio = (float)p_draw_data->fbWidth / (float)p_draw_data->winWidth;
            NVGcontext* nvgctx = wlights.nvgctx;
            nvgBeginFrame(nvgctx, p_draw_data->winWidth, p_draw_data->winHeight, pxRatio);
            {
                NVGpaint imgPaint;
                int imgw, imgh;
                // Black background
                nvgFillColor(nvgctx, nvgRGB(0, 0, 0));
                nvgBeginPath(nvgctx);
                nvgRect(nvgctx, 0, 0, p_draw_data->winWidth, p_draw_data->winHeight);
                nvgFill(nvgctx);
                // draws warning lights
                DrawWarnings(nvgctx, p_draw_data, &wlights);
            }
            nvgEndFrame(nvgctx);
        }
        break;
        //////////////////
        case PANEL_SERVICE_PRE_KILL:
        { 
            NVGcontext* nvgctx = wlights.nvgctx;
            nvgDeleteInternal(nvgctx);
            FlushVarList();        
        }
        break;
        //////////////////
        default:
            return false;
        } /////////////////////////
        return true;
    }
}

 

[Prepar3DGuy]

Someone had same issue ?

Yes, I have tried you module.
Unfortunately as stated in WASM's known limitations: "C++ exceptions are not supported." So you can't try-catch your exception.
But I have located the problem's point using ugly debug.

WASM: Compiled module DemoModule1.wasm in 58 seconds (Init: 0 ms / Compile: 1062 ms / Optim: 0 ms / Link Init: 749 ms / Link Generate: 56223 ms / Link LLVM: 107 ms).
WASM: Module DemoModule1.wasm loaded...
WASM: Module DemoModule1.wasm initialized.
Begin PANEL_SERVICE_PRE_INSTALL
Begin PANEL_SERVICE_POST_INSTALL
True  PANEL_SERVICE_POST_INSTALL
Begin PANEL_SERVICE_PRE_INITIALIZE
True  PANEL_SERVICE_PRE_INITIALIZE
Begin PANEL_SERVICE_POST_INITIALIZE
True  PANEL_SERVICE_POST_INITIALIZE
Begin PANEL_SERVICE_PRE_UPDATE
True  PANEL_SERVICE_PRE_UPDATE
Begin PANEL_SERVICE_POST_UPDATE
True  PANEL_SERVICE_POST_UPDATE
Begin PANEL_SERVICE_PRE_DRAW
DRAWING IF
WASM: Exception c000001d in gauge warning_panel in module C:\MSFS SDK\Samples\GaugeAircraft\Packages\mycompany-aircraft-wasm-gauge\SimObjects\Airplanes\MyCompany_Gauge_Aircraft\panel\DemoModule1.wasm

So the problem is in the first execution of case PANEL_SERVICE_PRE_DRAW and more precisely is that code inside DrawWarning, maybe Get() method or something else. I have placed blobs over the code I doesn't have.

....
        nvgFillColor(nvgctx, nvgRGB(250, 0, 0));
        fprintf(stderr, "DRAWING IF\n");
        if (data->rpm_overspeed->Get() > 0.0) {   // <----- Somewhere here
            sprintf(str, "RPM OVERSPEED");
            nvgText(nvgctx, 0, 0.10f * p_draw_data->winHeight, str, (const char*)NULL);
        }
    }
    fprintf(stderr, "DRAWING END\n");
....

After showing Exception the gauge doesn't work at all and corresponding dll is unloaded.

P.S. Ugly debug example.

#include <cstdio>
#include <map>

...
    
std::map<int, const char *> service_name = {
    {PANEL_SERVICE_PRE_QUERY, "PANEL_SERVICE_PRE_QUERY"},
    {PANEL_SERVICE_POST_QUERY, "PANEL_SERVICE_POST_QUERY"},
    {PANEL_SERVICE_PRE_INSTALL, "PANEL_SERVICE_PRE_INSTALL"},
    {PANEL_SERVICE_POST_INSTALL, "PANEL_SERVICE_POST_INSTALL"},
    {PANEL_SERVICE_PRE_INITIALIZE, "PANEL_SERVICE_PRE_INITIALIZE"},
    {PANEL_SERVICE_POST_INITIALIZE, "PANEL_SERVICE_POST_INITIALIZE"},
    {PANEL_SERVICE_PRE_UPDATE, "PANEL_SERVICE_PRE_UPDATE"},
    {PANEL_SERVICE_POST_UPDATE, "PANEL_SERVICE_POST_UPDATE"},
    {PANEL_SERVICE_PRE_GENERATE, "PANEL_SERVICE_PRE_GENERATE"},
    {PANEL_SERVICE_POST_GENERATE, "PANEL_SERVICE_POST_GENERATE"},
    {PANEL_SERVICE_PRE_DRAW, "PANEL_SERVICE_PRE_DRAW"},
    {PANEL_SERVICE_POST_DRAW, "PANEL_SERVICE_POST_DRAW"},
    {PANEL_SERVICE_PRE_KILL, "PANEL_SERVICE_PRE_KILL"},
    {PANEL_SERVICE_POST_KILL, "PANEL_SERVICE_POST_KILL"},
    {PANEL_SERVICE_CONNECT_TO_WINDOW, "PANEL_SERVICE_CONNECT_TO_WINDOW"},
    {PANEL_SERVICE_DISCONNECT, "PANEL_SERVICE_DISCONNECT"},
    {PANEL_SERVICE_PANEL_OPEN, "PANEL_SERVICE_PANEL_OPEN"},
    {PANEL_SERVICE_PANEL_CLOSE, "PANEL_SERVICE_PANEL_CLOSE"}
    };

extern "C" {
    MSFS_CALLBACK bool warning_panel_gauge_callback(FsContext ctx, int service_id, void* pData)
    {
        fprintf(stderr, "Begin %s\n", service_name[service_id]);
        switch (service_id)
        {
....
        default:
            fprintf(stderr, "False %s\n", service_name[service_id]);
            return false;
        }
        fprintf(stderr, "True  %s\n", service_name[service_id]);
        return true;
    }
}

 

[mariomotta]

Thanks a lot, will investigate further.
Error shows erratically, not always and more often during the initial load when the aircraft has been cached, the second load/compile does not show the error (i mean after click on "flight now")
/Mario