ShellPkg: Refine code by initializing local variable and adding ASSERT statement.

Add ASSERT statement and initialize local variable to make code more readable.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Qiu Shumin <shumin.qiu@intel.com>
Reviewed-by: Jaben Carsey <jaben.carsey@intel.com>


git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@18689 6f19259b-4bc3-4df7-8a09-765794883524

ShellPkg/Application/Shell/ShellProtocol.c

@@ -1633,6 +1633,8 @@ EfiShellExecute(
   UINTN                     Size;
   EFI_STATUS                CalleeStatusCode;
 
+  CalleeStatusCode = EFI_SUCCESS;
+  
   if ((PcdGet8(PcdShellSupportLevel) < 1)) {
     return (EFI_UNSUPPORTED);
   }

ShellPkg/Library/UefiShellTftpCommandLib/Tftp.c

@@ -341,6 +341,7 @@ ShellCommandRunTftp (
   }
 
   RemoteFilePath = ShellCommandLineGetRawValue (CheckPackage, 2);
+  ASSERT(RemoteFilePath != NULL);
   AsciiRemoteFilePath = AllocatePool (
                           (StrLen (RemoteFilePath) + 1) * sizeof (CHAR8)
                           );