diff --git a/classes/types/deck_type.gd b/classes/types/deck_type.gd
index d666dfd..f011c1a 100644
--- a/classes/types/deck_type.gd
+++ b/classes/types/deck_type.gd
@@ -19,7 +19,7 @@ func set_value(new_value: Variant) -> void:
 
 
 ## Virtual function. Used to convert [param other] to the overriding class' type.
-static func from(other: DeckType):
+static func from(other: DeckType) -> DeckType:
 	return null
 
 
@@ -53,7 +53,7 @@ class DeckTypeNumeric extends DeckType:
 	## [code]0.0[/code] for [code]false[/code].[br]
 	## In the case of [DeckType.DeckTypeString], converts to String if it is a valid number
 	## or [DeckType.DeckTypeError] otherwise.
-	static func from(other: DeckType):
+	static func from(other: DeckType) -> DeckType:
 		if other is DeckTypeNumeric:
 			return other
 
@@ -74,7 +74,7 @@ class DeckTypeNumeric extends DeckType:
 			return inst
 
 		var err: DeckTypeError = DeckTypeError.from(other)
-		err.error_message = "Conversion to Numeric is only possible from String or Bool."
+		err.error_message = "Conversion to Numeric is only possible from String or Bool"
 		return err
 
 
@@ -84,12 +84,13 @@ class DeckTypeString extends DeckType:
 		_value = value
 
 
-	static func from(other: DeckType):
+	static func from(other: DeckType) -> DeckTypeString:
 		if other is DeckTypeString:
 			return other
 
 		var inst := DeckTypeString.new()
 		inst._value = var_to_str(other.get_value())
+		return inst
 
 
 ## Boolean type. Corresponds to the JSON bool type.
@@ -103,7 +104,7 @@ class DeckTypeBool extends DeckType:
 	## if the value is a zero value ([code]0.0[/code] and [code]-0.0[/code]), [code]true[/code] otherwise.[br]
 	## In the case of [DeckType.DeckTypeDictionary] or [DeckType.DeckTypeArray],
 	## the resulting value will be [code]true[/code] if the container is not empty.
-	static func from(other: DeckType):
+	static func from(other: DeckType) -> DeckType:
 		if other is DeckTypeBool:
 			return other
 
@@ -117,6 +118,10 @@ class DeckTypeBool extends DeckType:
 			inst._value = !other.get_value().is_empty()
 			return inst
 
+		var err := DeckTypeError.from(other)
+		err.error_message = "Cannot create a DeckTypeBool from non-numeric or non-container type"
+		return err
+
 
 ## Array type. Corresponds to the JSON Array type.
 class DeckTypeArray extends DeckType:
@@ -126,14 +131,14 @@ class DeckTypeArray extends DeckType:
 
 	## Arrays can only be converted from a string in the format
 	## [code]"["foo", 2, "bar"][/code].
-	static func from(other: DeckType):
+	static func from(other: DeckType) -> DeckType:
 		if other is DeckTypeString:
 			var inst := DeckTypeArray.new()
 			inst._value = str_to_var(other.get_value())
 			return inst
 
 		var err: DeckTypeError = DeckTypeError.from(other)
-		err.error_message = "conversions to Array is only possible from String"
+		err.error_message = "Conversions to Array is only possible from String"
 		return err
 
 
@@ -145,7 +150,7 @@ class DeckTypeDictionary extends DeckType:
 
 	## Dictionaries can only be converted from a string in the format
 	## [code]{"key": "value"}[/code].
-	static func from(other: DeckType):
+	static func from(other: DeckType) -> DeckType:
 		if other is DeckTypeString:
 			var inst := DeckTypeDictionary.new()
 			inst._value = str_to_var(other.get_value())