refactor: default to npm in postinstall.sh

yarn has a bug where it will try to update dependencies even if
`yarn.lock` is present. Therefore we're defaulting to `npm` to prevent
further issues.

Author: jsjoeio

ci/build/npm-postinstall.sh

@@ -127,14 +127,6 @@ install_with_yarn_or_npm() {
   # NOTE@edvincent: We want to keep using the package manager that the end-user was using to install the package.
   # This also ensures that when *we* run `yarn` in the development process, the yarn.lock file is used.
   case "${npm_config_user_agent-}" in
-    yarn*)
-      if [ -f "yarn.lock" ]; then
-        yarn --production --frozen-lockfile --no-default-rc
-      else
-        echo "yarn.lock file not present, not running in development mode. use npm to install code-server!"
-        exit 1
-      fi
-      ;;
     npm*)
       if [ -f "yarn.lock" ]; then
         echo "yarn.lock file present, running in development mode. use yarn to install code-server!"
@@ -146,6 +138,14 @@ install_with_yarn_or_npm() {
         npm install --unsafe-perm --legacy-peer-deps --omit=dev
       fi
       ;;
+    yarn*)
+      if [ -f "yarn.lock" ]; then
+        yarn --production --frozen-lockfile --no-default-rc
+      else
+        echo "yarn.lock file not present, not running in development mode. use npm to install code-server!"
+        exit 1
+      fi
+      ;;
     *)
       echo "Could not determine which package manager is being used to install code-server"
       exit 1