From d9c1c7492494b981dbe2573487e43adf12700027 Mon Sep 17 00:00:00 2001
From: Grahame Grieve <grahameg@gmail.ccom>
Date: Tue, 21 May 2024 16:55:17 -0500
Subject: [PATCH] Fix NPEs in Liquid renderer

---
 .../java/org/hl7/fhir/r5/elementmodel/LanguageUtils.java | 3 ++-
 .../java/org/hl7/fhir/r5/renderers/LiquidRenderer.java   | 9 +++++++--
 .../main/java/org/hl7/fhir/r5/utils/LiquidEngine.java    | 8 +++++---
 3 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/elementmodel/LanguageUtils.java b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/elementmodel/LanguageUtils.java
index 928d5a726..fa957c861 100644
--- a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/elementmodel/LanguageUtils.java
+++ b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/elementmodel/LanguageUtils.java
@@ -285,7 +285,8 @@ public class LanguageUtils {
     if (element.isPrimitive() && isTranslatable(element)) {
       String base = element.primitiveValue();
       if (base != null) {
-        Set<TranslationUnit> tlist = findTranslations(pathForElement(element), base, translations);
+        String path = pathForElement(element);
+        Set<TranslationUnit> tlist = findTranslations(path, base, translations);
         for (TranslationUnit translation : tlist) {
           t++;
           if (!handleAsSpecial(parent, element, translation)) {
diff --git a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/renderers/LiquidRenderer.java b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/renderers/LiquidRenderer.java
index 6df205328..cb5a1afa5 100644
--- a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/renderers/LiquidRenderer.java
+++ b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/renderers/LiquidRenderer.java
@@ -144,8 +144,13 @@ public class LiquidRenderer extends ResourceRenderer implements ILiquidRendering
       } else {
         x.tx(base.toString());
       }
-      String res = new XhtmlComposer(true).compose(x).substring(5);
-      return res.substring(0, res.length()-6);
+      String res = new XhtmlComposer(true).compose(x);
+      res = res.substring(5);
+      if (res.length() < 6) {
+        return "";
+      } else {
+        return res.substring(0, res.length()-6);
+      }
     } catch (FHIRFormatError e) {
       throw new FHIRException(e);
     } catch (IOException e) {
diff --git a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/utils/LiquidEngine.java b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/utils/LiquidEngine.java
index dcec84d4b..fb7574ec9 100644
--- a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/utils/LiquidEngine.java
+++ b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/utils/LiquidEngine.java
@@ -231,9 +231,11 @@ public class LiquidEngine implements IEvaluationContext {
       StringBuilder b = new StringBuilder();
       boolean first = true;
       for (Base i : items) {
-        if (first) first = false; else b.append(", ");
-        String s = renderingSupport != null ? renderingSupport.renderForLiquid(ctxt.externalContext, i) : null;
-        b.append(s != null ? s : engine.convertToString(i));
+        if (i != null) {
+          if (first) first = false; else b.append(", ");
+          String s = renderingSupport != null ? renderingSupport.renderForLiquid(ctxt.externalContext, i) : null;
+          b.append(s != null ? s : engine.convertToString(i));
+        }
       }
       return b.toString();
     }