[patch] give a more helpful message when lts alias is mistakenly used

Author: r4reetik

nvm.sh

@@ -700,10 +700,12 @@ nvm_ensure_version_installed() {
       nvm_err "N/A: version \"${PREFIXED_VERSION:-$PROVIDED_VERSION}\" is not yet installed."
     fi
     nvm_err ""
-    if [ "${IS_VERSION_FROM_NVMRC}" != '1' ]; then
-        nvm_err "You need to run \`nvm install ${PROVIDED_VERSION}\` to install and use it."
-      else
-        nvm_err 'You need to run `nvm install` to install and use the node version specified in `.nvmrc`.'
+    if [ "${PROVIDED_VERSION}" = 'lts' ]; then
+      nvm_err '`lts` is not an alias - you may need to run `nvm install --lts` to install and `nvm use --lts` to use it.'
+    elif [ "${IS_VERSION_FROM_NVMRC}" != '1' ]; then
+      nvm_err "You need to run \`nvm install ${PROVIDED_VERSION}\` to install and use it."
+    else
+      nvm_err 'You need to run `nvm install` to install and use the node version specified in `.nvmrc`.'
     fi
     return 1
   fi

test/slow/nvm use/Running 'nvm use lts' shows actionable error

@@ -0,0 +1,19 @@
+#!/bin/sh
+
+set -ex
+
+die () { echo "$@" ; exit 1; }
+
+\. ../../../nvm.sh
+
+# Deactivate any active node version
+nvm deactivate >/dev/null 2>&1 || die 'deactivate failed'
+
+# Attempt to use 'lts' without '--' and capture the error message
+ERROR_OUTPUT=$(nvm use lts 2>&1) || true
+
+EXPECTED_ERROR='`lts` is not an alias - you may need to run `nvm install --lts` to install and `nvm use --lts` to use it.'
+
+# Check if the error message matches the expected output
+echo "$ERROR_OUTPUT" | grep -q "$EXPECTED_ERROR" \
+  || die "Expected error message not found. Got: $ERROR_OUTPUT"