Fix #147150: Crash when trying to merge vertex and edge

The operator passed edges into BM_edge_exists, which asserts both
inputs must be vertices. Mixed selections are now rejected with an
error message, preventing the assert and crash.

Ref !147239

source/blender/bmesh/intern/bmesh_marking.cc

@@ -1116,6 +1116,19 @@ void BM_select_history_validate(BMesh *bm)
   }
 }
 
+char BM_select_history_htype_all(const BMesh *bm)
+{
+  char htype_selected = 0;
+  LISTBASE_FOREACH (const BMEditSelection *, ese, &bm->selected) {
+    htype_selected |= ese->htype;
+    /* Early exit if all types found. */
+    if (htype_selected == (BM_VERT | BM_EDGE | BM_FACE)) {
+      break;
+    }
+  }
+  return htype_selected;
+}
+
 bool BM_select_history_active_get(BMesh *bm, BMEditSelection *ese)
 {
   BMEditSelection *ese_last = static_cast<BMEditSelection *>(bm->selected.last);

source/blender/bmesh/intern/bmesh_marking.hh

@@ -171,6 +171,10 @@ void _bm_select_history_store_after_notest(BMesh *bm, BMEditSelection *ese_ref,
 
 void BM_select_history_validate(BMesh *bm);
 void BM_select_history_clear(BMesh *bm);
+/**
+ * Get all element types present in a selection history.
+ */
+[[nodiscard]] char BM_select_history_htype_all(const BMesh *bm);
 /**
  * Get the active mesh element (with active-face fallback).
  */

source/blender/editors/mesh/editmesh_tools.cc

@@ -25,6 +25,7 @@
 #include "BLI_linklist.h"
 #include "BLI_linklist_stack.h"
 #include "BLI_listbase.h"
+#include "BLI_math_bits.h"
 #include "BLI_math_geom.h"
 #include "BLI_math_matrix.h"
 #include "BLI_math_rotation.h"
@@ -1542,6 +1543,7 @@ static wmOperatorStatus edbm_vert_connect_path_exec(bContext *C, wmOperator *op)
   ViewLayer *view_layer = CTX_data_view_layer(C);
   uint failed_selection_order_len = 0;
   uint failed_connect_len = 0;
+  bool has_select_history_mixed = false;
   const Vector<Object *> objects = BKE_view_layer_array_from_objects_in_edit_mode_unique_data(
       scene, view_layer, CTX_wm_view3d(C));
 
@@ -1563,6 +1565,14 @@ static wmOperatorStatus edbm_vert_connect_path_exec(bContext *C, wmOperator *op)
       continue;
     }
 
+    /* Skip mixed selections since path handling only supports uniform types, see #147150. */
+    const char htype_selected = BM_select_history_htype_all(bm);
+    if (count_bits_i(htype_selected) > 1) {
+      has_select_history_mixed = true;
+      failed_selection_order_len++;
+      continue;
+    }
+
     if (bm->selected.first) {
       BMEditSelection *ese = static_cast<BMEditSelection *>(bm->selected.first);
       if (ese->htype == BM_EDGE) {
@@ -1596,7 +1606,12 @@ static wmOperatorStatus edbm_vert_connect_path_exec(bContext *C, wmOperator *op)
   }
 
   if (failed_selection_order_len == objects.size()) {
-    BKE_report(op->reports, RPT_ERROR, "Invalid selection order");
+    if (has_select_history_mixed) {
+      BKE_report(op->reports, RPT_ERROR, "Could not connect mixed selection types");
+    }
+    else {
+      BKE_report(op->reports, RPT_ERROR, "Invalid selection order");
+    }
     return OPERATOR_CANCELLED;
   }
   if (failed_connect_len == objects.size()) {