[Beam] Move outDir/projectName derivation into generateBeamScaffold; language check first

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: dbrattli

src/Fable.Cli/Main.fs

@@ -1014,7 +1014,15 @@ let private compileBeamFiles (workingDir: string) =
              :: mainErlFiles)
         |> ignore
 
-let private generateBeamScaffold (outDir: string) (projectName: string) =
+let private generateBeamScaffold (cliArgs: CliArgs) =
+    let outDir =
+        cliArgs.OutDir
+        |> Option.defaultWith (fun () -> IO.Path.GetDirectoryName cliArgs.ProjectFile)
+
+    let projectName =
+        IO.Path.GetFileNameWithoutExtension(cliArgs.ProjectFile)
+        |> Pipeline.Beam.normalizeAppName
+
     let generatedMarker = "%% Generated by Fable - safe to regenerate"
     let fableModulesDir = IO.Path.Combine(outDir, "fable_modules")
 
@@ -1453,16 +1461,8 @@ let private compilationCycle (state: State) (changes: ISet<string>) =
                 }
 
             // Generate rebar3 scaffold for BEAM target after successful compilation
-            if not hasError && cliArgs.CompilerOptions.Language = Beam then
-                let outDir =
-                    cliArgs.OutDir
-                    |> Option.defaultWith (fun () -> IO.Path.GetDirectoryName cliArgs.ProjectFile)
-
-                let projectName =
-                    IO.Path.GetFileNameWithoutExtension(cliArgs.ProjectFile)
-                    |> Pipeline.Beam.normalizeAppName
-
-                generateBeamScaffold outDir projectName
+            if cliArgs.CompilerOptions.Language = Beam && not hasError then
+                generateBeamScaffold cliArgs
 
             // Run process
             let exitCode, state =