imgui: ignore invalid fonts when merging

Avoid crashing in release mode if a merged font is invalid or FontNo
can't be found. The font is simply ignored and the glyph range isn't
loaded.
Fixes MINIDUMP-4TD

core/deps/imgui/imgui_draw.cpp

@@ -2773,6 +2773,9 @@ static bool ImFontAtlasBuildWithStbTruetype(ImFontAtlas* atlas)
     dst_tmp_array.resize(atlas->Fonts.Size);
     memset(src_tmp_array.Data, 0, (size_t)src_tmp_array.size_in_bytes());
     memset(dst_tmp_array.Data, 0, (size_t)dst_tmp_array.size_in_bytes());
+    ImVector<bool> src_tmp_array_skip;
+    src_tmp_array_skip.resize(atlas->ConfigData.Size);
+    memset(src_tmp_array_skip.Data, 0, (size_t)src_tmp_array_skip.size_in_bytes());
 
     // 1. Initialize font loading structure, check font data validity
     for (int src_i = 0; src_i < atlas->ConfigData.Size; src_i++)
@@ -2797,7 +2800,8 @@ static bool ImFontAtlasBuildWithStbTruetype(ImFontAtlas* atlas)
         if (!stbtt_InitFont(&src_tmp.FontInfo, (unsigned char*)cfg.FontData, font_offset))
         {
             IM_ASSERT(0 && "stbtt_InitFont(): failed to parse FontData. It is correct and complete? Check FontDataSize.");
-            return false;
+            src_tmp_array_skip[src_i] = true;
+            continue;
         }
 
         // Measure highest codepoints
@@ -2818,6 +2822,8 @@ static bool ImFontAtlasBuildWithStbTruetype(ImFontAtlas* atlas)
     int total_glyphs_count = 0;
     for (int src_i = 0; src_i < src_tmp_array.Size; src_i++)
     {
+    	if (src_tmp_array_skip[src_i])
+    		continue;
         ImFontBuildSrcData& src_tmp = src_tmp_array[src_i];
         ImFontBuildDstData& dst_tmp = dst_tmp_array[src_tmp.DstIndex];
         src_tmp.GlyphsSet.Create(src_tmp.GlyphsHighest + 1);
@@ -2844,6 +2850,8 @@ static bool ImFontAtlasBuildWithStbTruetype(ImFontAtlas* atlas)
     // 3. Unpack our bit map into a flat list (we now have all the Unicode points that we know are requested _and_ available _and_ not overlapping another)
     for (int src_i = 0; src_i < src_tmp_array.Size; src_i++)
     {
+    	if (src_tmp_array_skip[src_i])
+    		continue;
         ImFontBuildSrcData& src_tmp = src_tmp_array[src_i];
         src_tmp.GlyphsList.reserve(src_tmp.GlyphsCount);
         UnpackBitVectorToFlatIndexList(&src_tmp.GlyphsSet, &src_tmp.GlyphsList);
@@ -2974,6 +2982,8 @@ static bool ImFontAtlasBuildWithStbTruetype(ImFontAtlas* atlas)
     // 9. Setup ImFont and glyphs for runtime
     for (int src_i = 0; src_i < src_tmp_array.Size; src_i++)
     {
+    	if (src_tmp_array_skip[src_i])
+    		continue;
         // When merging fonts with MergeMode=true:
         // - We can have multiple input fonts writing into a same destination font.
         // - dst_font->ConfigData is != from cfg which is our source configuration.