Fix exception in imports folding when there're two imports lists (KT-29455)

Probably caused by modifications of the recovery for import lists
https://github.com/JetBrains/kotlin/commit/65e6e21d0f3017417ecb786a63d5209c546dd744

 #KT-29455 Fixed

idea/src/org/jetbrains/kotlin/idea/KotlinFoldingBuilder.kt

@@ -35,8 +35,10 @@ import org.jetbrains.kotlin.idea.references.mainReference
 import org.jetbrains.kotlin.idea.references.resolveMainReferenceToDescriptors
 import org.jetbrains.kotlin.kdoc.lexer.KDocTokens
 import org.jetbrains.kotlin.lexer.KtTokens
-import org.jetbrains.kotlin.name.FqName
-import org.jetbrains.kotlin.psi.*
+import org.jetbrains.kotlin.psi.KtCallExpression
+import org.jetbrains.kotlin.psi.KtFile
+import org.jetbrains.kotlin.psi.KtFunctionLiteral
+import org.jetbrains.kotlin.psi.KtImportList
 import org.jetbrains.kotlin.psi.psiUtil.allChildren
 import org.jetbrains.kotlin.psi.psiUtil.endOffset
 import org.jetbrains.kotlin.psi.psiUtil.referenceExpression
@@ -66,17 +68,19 @@ class KotlinFoldingBuilder : CustomFoldingBuilder(), DumbAware {
         if (root !is KtFile) {
             return
         }
-        val imports = root.importDirectives
-        if (imports.size > 1) {
-            val importKeyword = imports[0].firstChild
-            val startOffset = importKeyword.endOffset + 1
 
-            val importList = root.importList
-            if (importList != null) {
+        val importList = root.importList
+        if (importList != null) {
+            val firstImport = importList.imports.firstOrNull()
+            if (firstImport != null && importList.imports.size > 1) {
+                val importKeyword = firstImport.firstChild
+
+                val startOffset = importKeyword.endOffset + 1
                 val endOffset = importList.endOffset
 
-                val range = TextRange(startOffset, endOffset)
-                descriptors.add(FoldingDescriptor(importList, range).apply { setCanBeRemovedWhenCollapsed(true) })
+                descriptors.add(FoldingDescriptor(importList, TextRange(startOffset, endOffset)).apply {
+                    setCanBeRemovedWhenCollapsed(true)
+                })
             }
         }
 

idea/testData/folding/checkCollapse/doubleImportListsError.kt

@@ -0,0 +1,8 @@
+// An empty import list in PSI
+inline fun foo() {}
+
+// Another import list in PSI
+import a.foo
+import a.inlineOnly
+
+fun box(): String {}

idea/tests/org/jetbrains/kotlin/idea/folding/KotlinFoldingTestGenerated.java

@@ -109,6 +109,11 @@ public class KotlinFoldingTestGenerated extends AbstractKotlinFoldingTest {
             runTest("idea/testData/folding/checkCollapse/customRegionsNotFullBlock.kt");
         }
 
+        @TestMetadata("doubleImportListsError.kt")
+        public void testDoubleImportListsError() throws Exception {
+            runTest("idea/testData/folding/checkCollapse/doubleImportListsError.kt");
+        }
+
         @TestMetadata("functionLiteral.kt")
         public void testFunctionLiteral() throws Exception {
             runTest("idea/testData/folding/checkCollapse/functionLiteral.kt");