diff --git a/src/Models/ThemeConfig/DependencyCalculator.ts b/src/Models/ThemeConfig/DependencyCalculator.ts
index eb1efebb2..1379917b1 100644
--- a/src/Models/ThemeConfig/DependencyCalculator.ts
+++ b/src/Models/ThemeConfig/DependencyCalculator.ts
@@ -15,8 +15,12 @@ export default class DependencyCalculator {
         }
         const deps: { id: string; minZoom?: number; neededBy: string }[] = []
 
-        if (tr.requiredLayers) {
-            deps.push(...tr.requiredLayers.map((req) => ({ ...req, neededBy: tr.id })))
+        for (const req of tr.requiredLayers ?? []) {
+            const dependency = { ...req, neededBy: tr.id }
+            if (!dependency.id) {
+                throw `The tagRendering ${tr.id} specifies a \`requiredBy\`, but this \`requiredBy\` does _not_ have an \`id\`-field`
+            }
+            deps.push(dependency)
         }
 
         // All translated snippets