I didn't know it worked for strict errors (or any other errors), so I tried it out. Turns out the diagnostic is even more cryptic than the original message, and misleading in mentioning references in what it usually a need to use a hash or array.
>perl -e"use diagnostics; use strict; print ${'x'}"
Can't use string ("x") as a SCALAR ref while "strict refs" in use at -
+e line 1 (#1)
(F) Only hard references are allowed by "strict refs". Symbolic
references are disallowed. See perlref.
Uncaught exception from user code:
Can't use string ("x") as a SCALAR ref while "strict refs" in
+use at -e line 1.
at -e line 1
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