From d44bfce66521e941a09204dab35ac7df2666b8d3 Mon Sep 17 00:00:00 2001
From: Xander Lenstra <71121390+xlenstra@users.noreply.github.com>
Date: Tue, 12 Oct 2021 06:30:20 +0200
Subject: [PATCH] Fixed crashes from era (#5467)

---
 core/src/com/unciv/logic/civilization/CivilizationInfo.kt | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/core/src/com/unciv/logic/civilization/CivilizationInfo.kt b/core/src/com/unciv/logic/civilization/CivilizationInfo.kt
index 81d4129a86..aa3879d121 100644
--- a/core/src/com/unciv/logic/civilization/CivilizationInfo.kt
+++ b/core/src/com/unciv/logic/civilization/CivilizationInfo.kt
@@ -544,8 +544,10 @@ class CivilizationInfo {
             .asSequence()
             .filter { it !in tech.researchedTechnologies }
             .map { it.column!! }
-            .minByOrNull { it.columnNumber }!!
-            .era
+            .minByOrNull { it.columnNumber }
+            ?.era
+            ?: return maxEra
+        
         val minEra = gameInfo.ruleSet.eras[minEraName]!!
 
         return if (minEra.eraNumber > maxEra.eraNumber) minEra