Add error when someone forgets npm install

run-selfhosted.js

@@ -1,27 +1,28 @@
+// surrounding_box function
+//
+// It's really hard to see an error message without using
+// the surrounding_box function to highlight its location.
+// The implementation of this in packages/backend might not
+// work in older versions of node, so we instead re-implement
+// it here.
+const surrounding_box = (col, lines) => {
+    const lengths = lines.map(line => line.length);
+
+    const max_length = Math.max(...lengths);
+    const c = str => `\x1b[${col}m${str}\x1b[0m`;
+    const bar = c(Array(max_length + 4).fill('━').join(''));
+    for ( let i = 0 ; i < lines.length ; i++ ) {
+        while ( lines[i].length < max_length ) {
+            lines[i] += ' ';
+        }
+        lines[i] = `${c('┃ ')} ${lines[i]} ${c(' ┃')}`;
+    }
+    lines.unshift(`${c('┏')}${bar}${c('┓')}`);
+    lines.push(`${c('┗')}${bar}${c('┛')}`);
+};
+
 // node version check
 {
-    // JUST AN AESTHETIC THING
-    // It's really hard to see the error message without using
-    // the surrounding_box function to highlight its location.
-    // The implementation of this in packages/backend might not
-    // work in older versions of node, so we instead re-implement
-    // it here.
-    const surrounding_box = (col, lines) => {
-        const lengths = lines.map(line => line.length);
-
-        const max_length = Math.max(...lengths);
-        const c = str => `\x1b[${col}m${str}\x1b[0m`;
-        const bar = c(Array(max_length + 4).fill('━').join(''));
-        for ( let i = 0 ; i < lines.length ; i++ ) {
-            while ( lines[i].length < max_length ) {
-                lines[i] += ' ';
-            }
-            lines[i] = `${c('┃ ')} ${lines[i]} ${c(' ┃')}`;
-        }
-        lines.unshift(`${c('┏')}${bar}${c('┓')}`);
-        lines.push(`${c('┗')}${bar}${c('┛')}`);
-    };
-
     // Keeping track of WHY certain versions don't work
     const ver_info = [
         { under: 14, reasons: ['optional chaining is not available'] },
@@ -48,7 +49,7 @@
     }
 }
 
-(async () => {
+const main = async () => {
     const {
         Kernel,
         CoreModule,
@@ -66,5 +67,64 @@
     k.add_module(new LocalDiskStorageModule());
     k.add_module(new SelfhostedModule()),
     k.boot();
-})();
+};
 
+const early_init_errors = [
+    {
+        text: `Cannot find package '@heyputer/backend'`,
+        notes: [
+            'this usually happens if you forget `npm install`'
+        ],
+        suggestions: [
+            'try running `npm install`'
+        ],
+        technical_notes: [
+            '@heyputer/backend is in an npm workspace'
+        ]
+    },
+    {
+        text: `Cannot find package`,
+        notes: [
+            'this usually happens if you forget `npm install`'
+        ],
+        suggestions: [
+            'try running `npm install`'
+        ],
+    }
+];
+
+const _print_error_help = (error_help) => {
+    const lines = [];
+    lines.push(error_help.title ?? error_help.text);
+    for ( const note of (error_help.notes ?? []) ) {
+        lines.push(`📝 ${note}`)
+    }
+    if ( error_help.suggestions ) {
+        lines.push('Suggestions:');
+        for ( const suggestion of error_help.suggestions ) {
+            lines.push(`- ${suggestion}`);
+        }
+    }
+    if ( error_help.technical_notes ) {
+        lines.push('Technical Notes:');
+        for ( const note of error_help.technical_notes ) {
+            lines.push(`- ${note}`);
+        }
+    }
+    surrounding_box('31;1', lines);
+    console.error(lines.join('\n'));
+}
+
+(async () => {
+    try {
+        await main();
+    } catch (e) {
+        for ( const error_help of early_init_errors ) {
+            if ( e?.message?.includes(error_help.text) ) {
+                _print_error_help(error_help);
+                break;
+            }
+        }
+        throw e;
+    }
+})();