fix(inspector): avoid double RefCell borrow #4297

Job	Run time
compute-jobs	3s
build-linux / linux lint	59s
build-linux-arm / linux-arm lint	1m 33s
build-linux / linux test	7m 46s
build-linux / linux test-miri	6m 19s
build-linux-arm / linux-arm test-miri	7m 11s
build-linux / linux lint-deps	1m 59s
build-linux / linux test-ops	8m 21s
build-linux-arm / linux-arm test	12m 0s
build-windows / windows test	17m 34s
build-macos / macos test	13m 50s
build-linux / linux coverage	18m 41s
build-windows / windows lint	2m 50s
build-linux / linux test-valgrind	24s
build-macos / macos lint	1m 16s
build-linux / linux test-publish	2m 4s
success	2s
	1h 42m 52s

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