Failed to decompress SourceSansPro-Semibold: %v

Error message

Failed to decompress SourceSansPro-Semibold: %v

What it means

init()-time panic in the wasm d2fonts package when the embedded brotli-compressed SourceSansPro Semibold font fails to decompress. The font cannot be registered in FontEncodings, so the module aborts at load time.

Source

Thrown at d2renderers/d2fonts/d2fonts_embed_wasm.go:67

func init() {
	FontEncodings = syncmap.New[Font, string]()

	// Decompress and register SourceSansPro fonts
	if str, err := compression.DecompressBrotli(sourceSansProRegularBr); err != nil {
		panic(fmt.Sprintf("Failed to decompress SourceSansPro-Regular: %v", err))
	} else {
		FontEncodings.Set(Font{Family: SourceSansPro, Style: FONT_STYLE_REGULAR}, str)
	}

	if str, err := compression.DecompressBrotli(sourceSansProBoldBr); err != nil {
		panic(fmt.Sprintf("Failed to decompress SourceSansPro-Bold: %v", err))
	} else {
		FontEncodings.Set(Font{Family: SourceSansPro, Style: FONT_STYLE_BOLD}, str)
	}

	if str, err := compression.DecompressBrotli(sourceSansProSemiboldBr); err != nil {
		panic(fmt.Sprintf("Failed to decompress SourceSansPro-Semibold: %v", err))
	} else {
		FontEncodings.Set(Font{Family: SourceSansPro, Style: FONT_STYLE_SEMIBOLD}, str)
	}

	if str, err := compression.DecompressBrotli(sourceSansProItalicBr); err != nil {
		panic(fmt.Sprintf("Failed to decompress SourceSansPro-Italic: %v", err))
	} else {
		FontEncodings.Set(Font{Family: SourceSansPro, Style: FONT_STYLE_ITALIC}, str)
	}

	// Decompress and register SourceCodePro fonts
	if str, err := compression.DecompressBrotli(sourceCodeProRegularBr); err != nil {
		panic(fmt.Sprintf("Failed to decompress SourceCodePro-Regular: %v", err))
	} else {
		FontEncodings.Set(Font{Family: SourceCodePro, Style: FONT_STYLE_REGULAR}, str)
	}

	if str, err := compression.DecompressBrotli(sourceCodeProBoldBr); err != nil {

View on GitHub (pinned to 0d69dca6f5)

Solutions

Validate sourceSansProSemiboldBr decompresses with a standalone brotli tool
Regenerate the .br asset via the project's embed script
Rebuild wasm from a clean upstream checkout
Check bundler config isn't mangling embedded binary blobs

Defensive patterns

Strategy: fallback

Validate before calling

if _, err := compression.DecompressBrotli(sourceSansProSemiboldBr); err != nil {
    return fmt.Errorf("broken embedded SourceSansPro-Semibold asset: %w", err)
}

Prevention

Regenerate all font .br assets together
Validate assets in CI before publishing
Keep brotli toolchain versions consistent
Rebuild from clean checkouts to avoid stale binaries

When it happens

Trigger: Package init of the wasm build when compression.DecompressBrotli(sourceSansProSemiboldBr) returns an error — corrupt, empty, or toolchain-incompatible embedded asset.

Common situations: Custom wasm builds with mis-generated semibold .br asset; bundler stripping/corrupting embedded binary assets; partial git checkout of binary files.

Related errors

AI-assisted analysis of d2lang/d2@0d69dca6f5 (2026-08-31). Data as JSON: /api/errors/5eb9d4483b554e86. Report an issue: GitHub.