[Fix] nvm exec: Do a version check on nvm-exec

This check would display a message in case the `.nvmrc` version is not installed, and would not alter the output otherwise.

nvm-exec

@@ -7,6 +7,7 @@ unset NVM_CD_FLAGS
 # shellcheck disable=SC1090,SC1091
 \. "$DIR/nvm.sh" --no-use
 
+nvm_rc_version > /dev/null && nvm_ensure_version_installed "$NVM_RC_VERSION";
 if [ -n "$NODE_VERSION" ]; then
   nvm use "$NODE_VERSION" > /dev/null || exit 127
 elif ! nvm use >/dev/null 2>&1; then

test/fast/Running 'nvm-exec' should display required node version

@@ -0,0 +1,18 @@
+#!/bin/bash
+
+set -x
+\. ../../nvm.sh
+
+NVM_TEST_VERSION=v0.42
+
+# Write it to nvmrc
+echo "$NVM_TEST_VERSION" > .nvmrc
+
+OUTPUT="$(../../nvm-exec 2>&1)";
+EXPECTED="N/A: version \`${NVM_TEST_VERSION}\` is not yet installed.
+
+You need to run \`nvm install ${NVM_TEST_VERSION}\` to install and use it.
+No NODE_VERSION provided; no .nvmrc file found";
+
+# Skip install, we want to test the error message
+diff <(echo "${EXPECTED}") <(echo "${OUTPUT}")