sadf (#18576)

code/modules/mob/language/language.dm

@@ -261,8 +261,22 @@
 		default_language = null
 	return ..()
 
-// Can we speak this language, as opposed to just understanding it?
+/**
+ * Check if the language can be spoken by the mob,
+ * not the same thing as understood (you can understand a language without speaking it)
+ *
+ * * speaking - The `/datum/language` to check against, if the mob can speak it
+ *
+ * Returns `TRUE` if the mob speaks the language, `FALSE` otherwise
+ */
 /mob/proc/can_speak(datum/language/speaking)
+	SHOULD_NOT_SLEEP(TRUE)
+	SHOULD_BE_PURE(TRUE)
+
+	if(!istype(speaking))
+		stack_trace("No language supplied to check if it can be spoken!")
+		return FALSE
+
 	return (speaking.check_speech_restrict(src) && (universal_speak || (speaking && speaking.flags & INNATE) || (speaking in src.languages)))
 
 /mob/proc/get_language_prefix()

code/modules/mob/say.dm

@@ -174,7 +174,7 @@
 			L = GLOB.language_keys[language_prefix]
 
 		//Check if we can speak the language, otherwise return null
-		if(can_speak(L))
+		if(istype(L) && can_speak(L))
 			return L
 		else
 			return null

html/changelogs/fluffyghost-fixcanspeakruntime2.yml

@@ -0,0 +1,42 @@
+################################
+# Example Changelog File
+#
+# Note: This file, and files beginning with ".", and files that don't end in ".yml" will not be read. If you change this file, you will look really dumb.
+#
+# Your changelog will be merged with a master changelog. (New stuff added only, and only on the date entry for the day it was merged.)
+# When it is, any changes listed below will disappear.
+#
+# Valid Prefixes:
+#   bugfix
+#   wip (For works in progress)
+#   tweak
+#   soundadd
+#   sounddel
+#   rscadd (general adding of nice things)
+#   rscdel (general deleting of nice things)
+#   imageadd
+#   imagedel
+#   maptweak
+#   spellcheck (typo fixes)
+#   experiment
+#   balance
+#   admin
+#   backend
+#   security
+#   refactor
+#################################
+
+# Your name.
+author: FluffyGhost
+
+# Optional: Remove this file after generating master changelog.  Useful for PR changelogs that won't get used again.
+delete-after: True
+
+# Any changes you've made.  See valid prefix list above.
+# INDENT WITH TWO SPACES.  NOT TABS.  SPACES.
+# SCREW THIS UP AND IT WON'T WORK.
+# Also, all entries are changed into a single [] after a master changelog generation. Just remove the brackets when you add new entries.
+# Please surround your changes in  double quotes ("), as certain characters otherwise screws up compiling. The quotes will not show up in the changelog.
+changes:
+  - bugfix: "Fixed yet another canspeak runtime."
+  - backend: "Added some SDMM markings, DMDoced the proc, added a guard in case the language is not supplied to the proc."