Fix base64 decode issue with short signal.me URLs.

app/src/main/java/org/thoughtcrime/securesms/profiles/manage/UsernameRepository.kt

@@ -311,7 +311,11 @@ object UsernameRepository {
   fun parseLink(url: String): UsernameLinkComponents? {
     val match: MatchResult = URL_REGEX.find(url) ?: return null
     val path: String = match.groups[2]?.value ?: return null
-    val allBytes: ByteArray = Base64.decode(path)
+    val allBytes: ByteArray = try {
+      Base64.decode(path)
+    } catch (e: IllegalArgumentException) {
+      return null
+    }
 
     if (allBytes.size != 48) {
       return null

app/src/test/java/org/thoughtcrime/securesms/profiles/manage/UsernameRepositoryTest.kt

@@ -0,0 +1,13 @@
+package org.thoughtcrime.securesms.profiles.manage
+
+import assertk.assertThat
+import assertk.assertions.isNull
+import org.junit.Test
+
+class UsernameRepositoryTest {
+  @Test
+  fun parseLink_one_character_base64_ref() {
+    val url = "https://signal.me/#eu/A"
+    assertThat(UsernameRepository.parseLink(url)).isNull()
+  }
+}