Fix vm_error stack trace

[obycode]

The Explorer will start showing the VM error outputs, so we may notice things that are off or could be improved. The first thing that was noticed, was that in some cases, it will print "Stack Trace: " but then not have any stack trace. This is coming from

stacks-core/clarity/src/vm/errors.rs

Line 142 in 9d53951

writeln!(f, "\n Stack Trace: ")?;

Example transaction with this problem: 11e24ddcd295a07334637e807727a42ce9bdb7528098578537ed5b5150e81e83

[lunargon]

Can I take a look with this ?

[obycode]

Sure, please @lunargon. PRs are welcome!