tpl/transform: Expose the KaTeX strict option

Closes #13729

tpl/transform/transform.go

@@ -19,6 +19,7 @@ import (
 	"context"
 	"encoding/xml"
 	"errors"
+	"fmt"
 	"html"
 	"html/template"
 	"io"
@@ -234,6 +235,7 @@ func (ns *Namespace) ToMath(ctx context.Context, args ...any) (template.HTML, er
 			MinRuleThickness: 0.04,
 			ErrorColor:       "#cc0000",
 			ThrowOnError:     true,
+			Strict:           "error",
 		},
 	}
 
@@ -243,6 +245,13 @@ func (ns *Namespace) ToMath(ctx context.Context, args ...any) (template.HTML, er
 		}
 	}
 
+	switch katexInput.Options.Strict {
+	case "error", "ignore", "warn":
+		// Valid strict mode, continue
+	default:
+		return "", fmt.Errorf("invalid strict mode; expected one of error, ignore, or warn; received %s", katexInput.Options.Strict)
+	}
+
 	s := hashing.HashString(args...)
 	key := "tomath/" + s[:2] + "/" + s[2:]
 	fileCache := ns.deps.ResourceSpec.FileCaches.MiscCache()