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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In reply to Re^2: Can't use string by ikegami
in thread Can't use string by Anonymous Monk

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