Fix CSV import preview crash on empty values (#756)

app/models/import/csv.rb

@@ -1,6 +1,6 @@
 class Import::Csv
   def self.parse_csv(csv_str)
-    CSV.parse((csv_str || "").strip, headers: true, converters: [ ->(str) { str.strip } ])
+    CSV.parse((csv_str || "").strip, headers: true, converters: [ ->(str) { str&.strip } ])
   end
 
   def self.create_with_field_mappings(raw_csv_str, fields, field_mappings)

test/models/import/csv_test.rb

@@ -36,6 +36,11 @@ class Import::CsvTest < ActiveSupport::TestCase
     assert_not invalid_csv.valid?
   end
 
+  test "csv with additional columns and empty values" do
+    csv = Import::Csv.new valid_csv_with_extra_column
+    assert csv.valid?
+  end
+
   test "updating a cell returns a copy of the original csv" do
     original_date = "2024-01-01"
     new_date = "2024-01-01"

test/support/import_test_helper.rb

@@ -14,6 +14,14 @@ module ImportTestHelper
     ROWS
   end
 
+  def valid_csv_with_extra_column
+    <<-ROWS
+      date,name,category,"optional id",amount
+      2024-01-01,Starbucks drink,Food,1234,20
+      2024-01-02,Amazon stuff,Shopping,,200
+    ROWS
+  end
+
   def malformed_csv_str
     <<-ROWS
       name,age