Thumbnail :uri values arrive from the server over transit, so
media-ids decode to UUID objects instead of strings. The
resolved-uri? helper added in #11563 called
clojure.string/starts-with? on them unconditionally, raising
TypeError: str.lastIndexOf is not a function and crashing the
workspace on frame render. Guard with string? so non-string
URIs fall through to resolve-media, which stringifies them.
AI-assisted-by: muse-spark-1.3-contributor
5d5f7fcc14