Move __deps type checking into mergeInto. NFC (#19045)

Doing the checks here gives better error message that include the
filename.

Author: sbc100

src/jsifier.js

@@ -251,10 +251,6 @@ function ${name}(${args}) {
       }
 
       const deps = LibraryManager.library[symbol + '__deps'] || [];
-      if (!Array.isArray(deps)) {
-        error(`JS library directive ${symbol}__deps=${deps.toString()} is of type ${typeof deps}, but it should be an array!`);
-        return;
-      }
 
       if (symbolsOnly) {
         if (!isJsOnlySymbol(symbol) && LibraryManager.library.hasOwnProperty(symbol)) {

src/utility.js

@@ -134,10 +134,17 @@ function mergeInto(obj, other, options = null) {
         const oldsig = obj[key];
         const newsig = other[key];
         if (oldsig != newsig) {
-          console.warn(`Signature redefinition mismatch for : ${key}. (old=${oldsig} vs new=${newsig})`);
+          error(`Signature redefinition for: ${key}. (old=${oldsig} vs new=${newsig})`);
         }
       }
     }
+
+    if (key.endsWith('__deps')) {
+      const deps = other[key];
+      if (!Array.isArray(deps)) {
+        error(`JS library directive ${key}=${deps.toString()} is of type ${typeof deps}, but it should be an array`);
+      }
+    }
   }
 
   return Object.assign(obj, other);

test/test_other.py

@@ -3839,16 +3839,56 @@ def test_js_internal_deps(self):
   },
 });
 ''')
-    create_file('src.cpp', r'''
+    create_file('src.c', r'''
 #include <stdio.h>
-extern "C" int jslibfunc();
+int jslibfunc();
 int main() {
   printf("c calling: %d\n", jslibfunc());
 }
 ''')
-    err = self.run_process([EMXX, 'src.cpp', '--js-library', 'lib.js'], stderr=PIPE).stderr
+    err = self.run_process([EMCC, 'src.c', '--js-library', 'lib.js'], stderr=PIPE).stderr
     self.assertContained("warning: user library symbol 'jslibfunc' depends on internal symbol '$callRuntimeCallbacks'", err)
 
+  def test_js_lib_sig_mismatch(self):
+    create_file('lib.js', r'''
+mergeInto(LibraryManager.library, {
+  jslibfunc__sig: 'ii',
+  jslibfunc: function(x) {},
+});
+
+mergeInto(LibraryManager.library, {
+  jslibfunc__sig: 'dd',
+  jslibfunc: function(x) {},
+});
+
+''')
+    create_file('src.c', r'''
+#include <stdio.h>
+int jslibfunc();
+int main() {
+  printf("c calling: %d\n", jslibfunc());
+}
+''')
+    err = self.expect_fail([EMCC, 'src.c', '--js-library', 'lib.js'])
+    self.assertContained('lib.js: Signature redefinition for: jslibfunc__sig. (old=ii vs new=dd)', err)
+
+  def test_js_lib_invalid_deps(self):
+    create_file('lib.js', r'''
+mergeInto(LibraryManager.library, {
+  jslibfunc__deps: 'hello',
+  jslibfunc: function(x) {},
+});
+''')
+    create_file('src.c', r'''
+#include <stdio.h>
+int jslibfunc();
+int main() {
+  printf("c calling: %d\n", jslibfunc());
+}
+''')
+    err = self.expect_fail([EMCC, 'src.c', '--js-library', 'lib.js'])
+    self.assertContained('lib.js: JS library directive jslibfunc__deps=hello is of type string, but it should be an array', err)
+
   def test_EMCC_BUILD_DIR(self):
     # EMCC_BUILD_DIR env var contains the dir we were building in, when running the js compiler (e.g. when
     # running a js library). We force the cwd to be src/ for technical reasons, so this lets you find out