Fix error message about accessing storage pointers.

test/libsolidity/syntaxTests/controlFlow/uninitializedAccess/assembly.sol

@@ -6,4 +6,4 @@ contract C {
     }
 }
 // ----
-// TypeError: (92-116): This variable is of storage pointer type and can be accessed without prior assignment.
+// TypeError: (92-116): This variable is of storage pointer type and can be accessed without prior assignment, which would lead to undefined behaviour.

test/libsolidity/syntaxTests/controlFlow/uninitializedAccess/modifier_order_fail.sol

@@ -5,4 +5,4 @@ contract C {
     function f() m1(b) m2(b = s) internal view returns (uint[] storage b) {}
 }
 // ----
-// TypeError: (129-130): This variable is of storage pointer type and can be accessed without prior assignment.
+// TypeError: (129-130): This variable is of storage pointer type and can be accessed without prior assignment, which would lead to undefined behaviour.

test/libsolidity/syntaxTests/controlFlow/uninitializedAccess/modifier_post_access.sol

@@ -10,4 +10,4 @@ contract C {
     }
 }
 // ----
-// TypeError: (120-121): This variable is of storage pointer type and can be accessed without prior assignment.
+// TypeError: (120-121): This variable is of storage pointer type and can be accessed without prior assignment, which would lead to undefined behaviour.

test/libsolidity/syntaxTests/controlFlow/uninitializedAccess/modifier_pre_access.sol

@@ -10,4 +10,4 @@ contract C {
     }
 }
 // ----
-// TypeError: (120-121): This variable is of storage pointer type and can be accessed without prior assignment.
+// TypeError: (120-121): This variable is of storage pointer type and can be accessed without prior assignment, which would lead to undefined behaviour.

test/libsolidity/syntaxTests/controlFlow/uninitializedAccess/smoke.sol

@@ -7,4 +7,4 @@ contract C {
     }
 }
 // ----
-// TypeError: (94-95): This variable is of storage pointer type and can be accessed without prior assignment.
+// TypeError: (94-95): This variable is of storage pointer type and can be accessed without prior assignment, which would lead to undefined behaviour.

test/libsolidity/syntaxTests/controlFlow/uninitializedAccess/struct.sol

@@ -8,4 +8,4 @@ contract C {
     }
 }
 // ----
-// TypeError: (109-110): This variable is of storage pointer type and can be accessed without prior assignment.
+// TypeError: (109-110): This variable is of storage pointer type and can be accessed without prior assignment, which would lead to undefined behaviour.