Logger can take in exceptions according to documentation so stringify…

… first

Docs: https://ruby-doc.org/stdlib-2.5.0/libdoc/logger/rdoc/Logger.html\#method-i-add-label-Args

lib/raven/breadcrumbs/logger.rb

@@ -36,7 +36,7 @@ def add_breadcrumb(severity, message = nil, progname = nil)
 
       # some loggers will add leading/trailing space as they (incorrectly, mind you)
       # think of logging as a shortcut to std{out,err}
-      message = message.strip
+      message = message.to_s.strip
 
       last_crumb = Raven.breadcrumbs.peek
       # try to avoid dupes from logger broadcasts

spec/raven/logger_spec.rb

@@ -9,4 +9,13 @@
 
     expect(stringio.string).to end_with("FATAL -- sentry: ** [Raven] Oh noes!\n")
   end
+
+  it "should allow exceptions to be logged" do
+    stringio = StringIO.new
+    log = Raven::Logger.new(stringio)
+
+    log.fatal(Exception.new("Oh exceptions"))
+
+    expect(stringio.string).to end_with("FATAL -- sentry: ** [Raven] Oh exceptions\n")
+  end
 end