diff --git a/lib/rambling/trie.rb b/lib/rambling/trie.rb
index 04c8fe23..e3b84a0c 100644
--- a/lib/rambling/trie.rb
+++ b/lib/rambling/trie.rb
@@ -26,7 +26,7 @@ def create filepath = nil, reader = nil
           if filepath
             reader ||= readers.resolve filepath
             # noinspection RubyMismatchedArgumentType,RubyNilAnalysis
-            reader.each_word filepath do |word|
+            (reader || raise).each_word filepath do |word|
               container << word
             end
           end
@@ -48,7 +48,7 @@ def create filepath = nil, reader = nil
       #   discouraged. Only use the +.marshal+ format with trusted input.
       def load filepath, serializer = nil
         serializer ||= serializers.resolve filepath
-        root = serializer.load filepath
+        root = (serializer || raise).load filepath
         Rambling::Trie::Container.new root, compressor do |container|
           yield container if block_given?
         end
@@ -66,7 +66,7 @@ def load filepath, serializer = nil
       def dump trie, filepath, serializer = nil
         serializer ||= serializers.resolve filepath
         # noinspection RubyNilAnalysis
-        serializer.dump trie.root, filepath
+        (serializer || raise).dump trie.root, filepath
       end
 
       # Provides configuration properties for the +Rambling::Trie+ gem.
diff --git a/lib/rambling/trie/configuration/provider_collection.rb b/lib/rambling/trie/configuration/provider_collection.rb
index 7e827433..059467e4 100644
--- a/lib/rambling/trie/configuration/provider_collection.rb
+++ b/lib/rambling/trie/configuration/provider_collection.rb
@@ -104,7 +104,9 @@ def file_format filepath
         end
 
         def contains? provider
-          provider.nil? || (providers.any? && provider_instances.include?(provider))
+          return true if provider.nil?
+          p = (provider || raise)
+          providers.any? && provider_instances.include?(p)
         end
 
         alias_method :provider_instances, :values
diff --git a/lib/rambling/trie/nodes/compressed.rb b/lib/rambling/trie/nodes/compressed.rb
index eecc4041..d9fcc8ce 100644
--- a/lib/rambling/trie/nodes/compressed.rb
+++ b/lib/rambling/trie/nodes/compressed.rb
@@ -23,13 +23,13 @@ def compressed?
         private
 
         def partial_word_chars? chars
-          child = children_tree[chars.first.to_sym]
+          child = children_tree[(chars.first || raise).to_sym]
           return false unless child
 
           child_letter = child.letter.to_s
 
           if chars.size >= child_letter.size
-            letter = chars.slice!(0, child_letter.size).join
+            letter = (chars.slice!(0, child_letter.size) || raise).join
             return child.partial_word? chars if child_letter == letter
           end
 
@@ -39,7 +39,7 @@ def partial_word_chars? chars
         end
 
         def word_chars? chars
-          letter = chars.slice! 0
+          letter = chars.slice!(0) || raise
           letter_sym = letter.to_sym
 
           child = children_tree[letter_sym]
@@ -50,7 +50,7 @@ def word_chars? chars
 
             break if chars.empty?
 
-            letter << chars.slice!(0)
+            letter << (chars.slice!(0) || raise)
             letter_sym = letter.to_sym
           end
 
@@ -58,13 +58,13 @@ def word_chars? chars
         end
 
         def closest_node chars
-          child = children_tree[chars.first.to_sym]
+          child = children_tree[(chars.first || raise).to_sym]
           return missing unless child
 
           child_letter = child.letter.to_s
 
           if chars.size >= child_letter.size
-            letter = chars.slice!(0, child_letter.size).join
+            letter = (chars.slice!(0, child_letter.size) || raise).join
             return child.scan chars if child_letter == letter
           end
 
@@ -79,11 +79,11 @@ def children_match_prefix chars
 
           return EMPTY_ENUMERATOR if chars.empty?
 
-          child = children_tree[chars.first.to_sym]
+          child = children_tree[(chars.first || raise).to_sym]
           return EMPTY_ENUMERATOR unless child
 
           child_letter = child.letter.to_s
-          letter = chars.slice!(0, child_letter.size).join
+          letter = (chars.slice!(0, child_letter.size) || raise).join
 
           return EMPTY_ENUMERATOR unless child_letter == letter
 
diff --git a/lib/rambling/trie/nodes/raw.rb b/lib/rambling/trie/nodes/raw.rb
index 1fefacad..1c3558d3 100644
--- a/lib/rambling/trie/nodes/raw.rb
+++ b/lib/rambling/trie/nodes/raw.rb
@@ -27,7 +27,7 @@ def compressed?
         private
 
         def add_to_children_tree chars
-          letter = chars.pop
+          letter = chars.pop || raise
           child = children_tree[letter] || new_node(letter)
           child.add chars
           child
@@ -40,7 +40,7 @@ def new_node letter
         end
 
         def partial_word_chars? chars = []
-          letter = chars.shift.to_sym
+          letter = (chars.shift || raise).to_sym
           child = children_tree[letter]
           return false unless child
 
@@ -48,7 +48,7 @@ def partial_word_chars? chars = []
         end
 
         def word_chars? chars = []
-          letter = chars.shift.to_sym
+          letter = (chars.shift || raise).to_sym
           child = children_tree[letter]
           return false unless child
 
@@ -56,7 +56,7 @@ def word_chars? chars = []
         end
 
         def closest_node chars
-          letter = chars.shift.to_sym
+          letter = (chars.shift || raise).to_sym
           child = children_tree[letter]
           return missing unless child
 
@@ -68,7 +68,7 @@ def children_match_prefix chars
 
           return EMPTY_ENUMERATOR if chars.empty?
 
-          letter = chars.shift.to_sym
+          letter = (chars.shift || raise).to_sym
           child = children_tree[letter]
 
           return EMPTY_ENUMERATOR unless child
diff --git a/lib/rambling/trie/serializers/zip.rb b/lib/rambling/trie/serializers/zip.rb
index 809fbc9f..740b63b9 100644
--- a/lib/rambling/trie/serializers/zip.rb
+++ b/lib/rambling/trie/serializers/zip.rb
@@ -26,12 +26,14 @@ def load filepath
 
           ::Zip::File.open filepath do |zip|
             entry = zip.entries.first
-            return nil if entry.nil?
+            raise if entry.nil?
 
             entry_path = path entry.name
             entry.extract entry_path
 
             serializer = serializers.resolve entry.name
+            raise if serializer.nil?
+
             serializer.load entry_path
           end
         end
@@ -50,6 +52,8 @@ def dump contents, filepath
 
             entry_path = path filename
             serializer = serializers.resolve filename
+
+            raise if serializer.nil?
             serializer.dump contents, entry_path
 
             zip.add filename, entry_path