Use nvm_version_dir in nvm_version_path

nvm.sh

@@ -112,9 +112,10 @@ nvm_version_path() {
   local VERSION
   VERSION="$1"
   if [ -z "$VERSION" ]; then
-    echo "$NVM_DIR"
+    echo "version is required" >&2
+    return 3
   elif [ ! -z "$VERSION" ]; then
-    echo "$NVM_DIR/$VERSION"
+    echo "$(nvm_version_dir old)/$VERSION"
   fi
 }
 

test/fast/Unit tests/nvm_version_path

@@ -4,6 +4,6 @@ die () { echo $@ ; exit 1; }
 
 . ../../../nvm.sh
 
-[ "$(nvm_version_path)" = "$NVM_DIR" ] &&
-[ "$(nvm_version_path foo)" = "$NVM_DIR/foo" ]
+[ "$(nvm_version_path foo)" = "$NVM_DIR/foo" ] || die '"nvm_version_path foo" did not return correct location'
+[ "$(nvm_version_path 2>&1)" = "version is required" ] || die '"nvm_version_path" did not error out'