Show error message when all Page Templates are removed.

generator/src/codegen.js

@@ -13,6 +13,8 @@ async function generate() {
 }
 
 async function writeFiles() {
+  const cliCode = generateTemplateModuleConnector("cli");
+  const browserCode = generateTemplateModuleConnector("browser");
   ensureDirSync("./elm-stuff");
   ensureDirSync("./gen");
   ensureDirSync("./elm-stuff/elm-pages");
@@ -31,13 +33,11 @@ async function writeFiles() {
 
   // write `Pages.elm` with cli interface
   fs.writeFileSync("./elm-stuff/elm-pages/Pages.elm", elmPagesCliFile());
-  const cliCode = generateTemplateModuleConnector("cli");
   fs.writeFileSync(
     "./elm-stuff/elm-pages/TemplateModulesBeta.elm",
     cliCode.mainModule
   );
   fs.writeFileSync("./elm-stuff/elm-pages/Route.elm", cliCode.routesModule);
-  const browserCode = generateTemplateModuleConnector("browser");
   fs.writeFileSync("./gen/TemplateModulesBeta.elm", browserCode.mainModule);
   fs.writeFileSync("./gen/Route.elm", browserCode.routesModule);
 

generator/src/dev-server.js

@@ -113,12 +113,26 @@ async function start(options) {
     } else if (pathThatChanged.endsWith(".elm")) {
       if (elmMakeRunning) {
       } else {
+        let codegenError = null;
         if (needToRerunCodegen(eventName, pathThatChanged)) {
-          await codegen.generate();
+          try {
+            await codegen.generate();
+          } catch (error) {
+            codegenError = error;
+          }
         }
         elmMakeRunning = true;
-        clientElmMakeProcess = compileElmForBrowser();
-        pendingCliCompile = compileCliApp();
+        if (codegenError) {
+          const errorJson = JSON.stringify({
+            type: "compile-errors",
+            errors: [codegenError],
+          });
+          clientElmMakeProcess = Promise.reject(errorJson);
+          pendingCliCompile = Promise.reject(errorJson);
+        } else {
+          clientElmMakeProcess = compileElmForBrowser();
+          pendingCliCompile = compileCliApp();
+        }
         let timestamp = Date.now();
 
         Promise.all([clientElmMakeProcess, pendingCliCompile])

generator/src/generate-template-module-connector.js

@@ -16,7 +16,24 @@ function generateTemplateModuleConnector(phase) {
     }
   });
   if (templates.length <= 0) {
-    throw `I couldn't find any Page Templates. Try using elm-pages add Index to get started with your first page!`;
+    throw {
+      path: "",
+      name: "TemplateModulesBeta",
+      problems: [
+        {
+          title: "Could not generate entrypoint",
+          message: [
+            `I couldn't find any Page Templates. Try creating your first page by running: \n\n`,
+            {
+              bold: false,
+              underline: false,
+              color: "yellow",
+              string: "elm-pages add Index",
+            },
+          ],
+        },
+      ],
+    };
   }
 
   return {