Fix formatter crash on backtrace lines without file:line format

lib/ruby_lsp/ruby_lsp_rspec/rspec_formatter.rb

@@ -80,6 +80,8 @@ def generate_id(example)
       def adjust_backtrace(backtrace)
         # Correct the backtrace entry so that vscode recognized it as a link to open
         parts = backtrace.split(":", 3)
+        return backtrace if parts.length < 2
+
         parts[0].sub(/^\./, "file://" + File.expand_path(".")) + ":" + parts[1] + " : " + (parts[2] || "")
       end
     end

spec/fixtures/chained_exception_spec.rb

@@ -0,0 +1,15 @@
+# frozen_string_literal: true
+
+require_relative "../../lib/ruby_lsp/ruby_lsp_rspec/rspec_formatter"
+
+RSpec.configure do |config|
+  config.formatter = "RubyLsp::RSpec::RSpecFormatter"
+end
+
+RSpec.describe "ChainedExceptionExample" do
+  it "fails with a chained error" do
+    raise "secondary error"
+  rescue
+    raise "primary error"
+  end
+end

spec/rspec_formatter_spec.rb

@@ -154,6 +154,15 @@
     expect(events).to match(expected)
   end
 
+  it "does not crash when formatting backtrace from chained exceptions" do
+    fixture_path = File.expand_path("spec/fixtures/chained_exception_spec.rb")
+
+    stdout, stderr, = Open3.capture3("bundle", "exec", "rspec", fixture_path)
+
+    output = stdout + stderr
+    expect(output).not_to include("adjust_backtrace")
+  end
+
   describe "RubyLsp::RSpec::RSpecFormatter notifications" do
     let(:output) { StringIO.new }
     let(:formatter) { RubyLsp::RSpec::RSpecFormatter.new(output) }