Fix NoMethodError when passing invalid path to --collection

Before:

```console
$ bundle exec exe/typeprof smoke/simple.rb --collection=foo.yml
bundler: failed to load command: exe/typeprof (exe/typeprof)
/.../typeprof/lib/typeprof/cli.rb:108:in `parse': undefined method `exist?' for "foo.yml":String (NoMethodError)

      if !no_collection && (collection_path && !collection_path.exist?)
                                                               ^^^^^^^
```

After:

```console
$ bundle exec exe/typeprof smoke/simple.rb --collection=foo.yml
invalid option: collection path not found (foo.yml)

$ bundle exec exe/typeprof smoke/simple.rb --collection=foo.yml --no-collection
# TypeProf 0.21.7
...
```

lib/typeprof/cli.rb

@@ -23,7 +23,8 @@ def parse(argv)
       gem_rbs_features = []
       show_version = false
       max_sec = max_iter = nil
-      collection_path = RBS::Collection::Config::PATH
+      collection_path = nil
+      no_collection = false
 
       load_path_ext = []
 
@@ -35,8 +36,8 @@ def parse(argv)
       opt.on("--version", "Display typeprof version") { show_version = true }
       opt.on("-I DIR", "Add DIR to the load/require path") {|v| load_path_ext << v }
       opt.on("-r FEATURE", "Require RBS of the FEATURE gem") {|v| gem_rbs_features << v }
-      opt.on("--collection PATH", "File path of collection configuration") { |v| collection_path = v }
-      opt.on("--no-collection", "Ignore collection configuration") { collection_path = nil }
+      opt.on("--collection PATH", "File path of collection configuration") { |v| collection_path = Pathname(v) }
+      opt.on("--no-collection", "Ignore collection configuration") { no_collection = true }
       opt.on("--lsp", "LSP mode") {|v| options[:lsp] = true }
 
       opt.separator ""
@@ -104,6 +105,14 @@ def parse(argv)
         raise OptionParser::InvalidOption.new("lsp options with non-lsp mode")
       end
 
+      if !no_collection && collection_path && !collection_path.exist?
+        exit if show_version
+        raise OptionParser::InvalidOption.new("collection path not found (#{collection_path})")
+      end
+
+      collection_path ||= RBS::Collection::Config::PATH
+      collection_path = nil if no_collection
+
       ConfigData.new(
         rb_files: rb_files,
         rbs_files: rbs_files,