Add katex option ThrowOnError

As an internal option for now. Katex misbehaves in error situations without a value set.

internal/warpc/katex.go

@@ -37,6 +37,10 @@ type KatexOptions struct {
 
 	// Specifies a minimum thickness, in ems, for fraction lines.
 	MinRuleThickness float64 `json:"minRuleThickness"`
+
+	// If true, KaTeX will throw a ParseError when it encounters an unsupported command.
+	// For internal use only, for now.
+	ThrowOnError bool `json:"throwOnError"`
 }
 
 type KatexOutput struct {

tpl/transform/transform.go

@@ -223,6 +223,9 @@ func (ns *Namespace) ToMath(ctx context.Context, args ...any) (template.HTML, er
 		}
 	}
 
+	// Make sure this isn't set by the client (for now).
+	katexInput.Options.ThrowOnError = false
+
 	s := hashing.HashString(args...)
 	key := "tomath/" + s[:2] + "/" + s[2:]
 	fileCache := ns.deps.ResourceSpec.FileCaches.MiscCache()