PlatformWasm hands the runtime the module to run as a path on the host
it launches the runtime on. It takes that path from the launch info,
whose executable is the name the module goes by on the platform. That
name is whatever a stub reported the module under, which need not be a
path that resolves on this host, so a relaunch runs a file that does not
exist:
```
(lldb) run
error: WebAssembly runtime exited with exit code 255
```
Run the file the target has instead. Only a runtime launched on this
host is affected, since a connection to a remote Wasm platform delegates
the launch to that platform.
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