fixes #8371, macros.hasCustomPragma doesn't crash anymore (#8378)

* fixes #8371, macros.hasCustomPragma doesn't crash anymore

* fix macros.hasCustomPragma

lib/core/macros.nim

@@ -1319,6 +1319,8 @@ proc customPragmaNode(n: NimNode): NimNode =
           if identDefs.kind == nnkRecCase:
             identDefsStack.add(identDefs[0])
             for i in 1..<identDefs.len:
+              # if it is and empty branch, skip
+              if identDefs[i][0].kind == nnkNilLit: continue
               if identDefs[i][1].kind == nnkIdentDefs:
                 identDefsStack.add(identDefs[i][1])
               else: # nnkRecList

tests/pragmas/tcustom_pragma.nim

@@ -154,3 +154,23 @@ block:
 let a: proc(x: int) {.defaultValue(5).} = nil
 static:
   doAssert hasCustomPragma(a.type, defaultValue)
+
+# bug #8371
+template thingy {.pragma.}
+
+type
+  Cardinal = enum
+    north, east, south, west
+  Something = object
+    a: float32
+    case cardinal: Cardinal
+    of north:
+      b {.thingy.}: int
+    of east:
+      c: int
+    of south: discard
+    else: discard
+
+var foo: Something
+foo.cardinal = north
+doAssert foo.b.hasCustomPragma(thingy) == true